A phase control device outputs, after the elapse of a delay time, a closing control signal or an opening control signal in response to a command to open or a command to close a circuit breaker such that the circuit breaker is open or closed at a target phase, or a phase that is targeted (see Patent Literature 1).
In recent years, phase control devices have become widely used to control phase-regulation circuit breakers that close or open phase regulation equipment (e.g., a shunt reactor or a shunt capacitor) in order to regulate the reactive power in power systems.
However, a target phase of the time when a circuit breaker is open or closed depends on the phase of the three-phase alternating voltage and current signals input to the phase control device. Thus, if there is an error in the input of a three-phase alternating voltage or current signal, it is not possible to obtain a desired phase. Therefore, three-phase voltage and current measurement wiring that connects the phase control device and the circuit breaker needs to be connected accurately.
Connection error detection is widely performed in devices that measure electric power or the like, and a method of detecting connection errors using the product of the values of the voltage and the current is known (see Patent Literature 2).